South Fork Research Articles

Recovery of thermophilic Campylobacter by three sampling methods from river sites in Northeast Georgia, USA, and their antimicrobial resistance genes.

Sixteen sites in the watershed of the South Fork of the Broad River (SFBR) in Northeastern Georgia, USA, were sampled in two seasons to detect Campylobacter. Sites were classified as mostly influenced by forest, pasture, wastewater pollution control plants (WPC) or mixed use. Sampling was repeated in the late spring and late fall for 2years for a total of 126 samples. Free-catch water and sediment grab samples were taken at each site; Moore's swabs were placed for up to 3days at most sites. A total of 56 isolates of thermophilic Campylobacter were recovered. Thirteen samplings were positive by two or three methods, and 26 samplings were positive by only one method; once by Moore's swab only and 25 times by free-catch water only. Campylobacter was detected at 58% of cattle pasture sites, 30% of forested sites and 81% of WPC sites. Twenty-one of the isolates carried antimicrobial resistance genes, mostly blaOXA-61. Free-catch water samples were more efficient than Moore's swabs or sediment samples for recovery of Campylobacter, which was more likely to be detected in streams near cattle pastures and human communities than in forested land. SIGNIFICANCE AND IMPACT OF THE STUDY: The role of environmental water in transmitting Campylobacter was investigated, and methods for recovery of the organism were compared. The sequence types of recovered Campylobacter correlated with adjacent land use without regard to the method used to isolate the organisms. Sequence types and antimicrobial resistance genes associated with cattle were most prevalent near pastures. Even though types were recurrent at a given site, types appeared to be lost or replaced as the water flowed downstream.

Do genomics and sex predict migration in a partially migratory salmonid fish,Oncorhynchus mykiss?

Partial migration is a common phenomenon wherein populations include migratory and resident individuals. Whether an individual migrates or not has important ecological and management implications, particularly within protected populations. Within partially migratory populations of Oncorhynchus mykiss, migration is highly correlated with a specific genomic region, but it is unclear how well this region predicts migration at the individual level. Here, we relate sex and life history genotype, determined using >400 single nucleotide polymorphisms (SNPs) on the migratory-linked genomic region, to life history expression of marked juvenile O. mykiss from two tributaries to the South Fork Eel River, northern California. Most resident fish were resident genotypes (57% resident, 37% heterozygous, 6% migratory genotype) and male (78%). Most migratory fish were female (62%), but were a mixture of genotypes (30% resident, 45% heterozygous, 25% migratory genotype). Sex was more strongly correlated with life history expression than genotype, but the best-supported model included both. Resident genotypes regularly migrated, highlighting the importance of conserving the full suite of life history and genetic diversity in partially migratory populations.

Drones, hydraulics, and climate change: Inferring barriers to steelhead spawning migrations

AbstractGlobal climate models suggest dramatic changes in the timing and form of future precipitation in the Pacific Northwest, United States. By some estimates, in the Columbia River drainage, basin‐wide snow‐water equivalencies could decrease by more than 50% before the end of the century, with locally more extreme variation. In the South Fork Clearwater River, Idaho, where hydraulic barriers are currently thought to partially limit ESA‐listed steelhead migrations, changes in precipitation that could exacerbate the intensity and timing of hydraulic barriers presents an obvious conservation concern. Evidence indicates that the strongest steelhead swimmers are capable of sustaining burst speeds for up to 20 s, with maximum speed being a function of fish size (length). Understanding hydraulic dynamics that have implications for migrating fish requires integration of high‐resolution hydraulic models with sufficient resolution to characterize the hydraulic experience of the fish. Unmanned aerial vehicles (drones) have recently emerged as useful platforms for measuring river ecosystems with high precision. Results from habitat surveys and hydraulic modeling can identify locations where intense hydraulic energy may preclude fish passage during critical migration periods. The current as well as future range of discharges can be evaluated with a spatially explicit hydraulic model to quantify when, where, and how long barriers to migration exist. Further, this approach provides a powerful tool for manipulating the digital physical channel form and presents a heuristic opportunity to test hydraulic scenarios to improve migration success.This article is categorized under: Water and Life > Nature of Freshwater Ecosystems Water and Life > Stresses and Pressures on Ecosystems Water and Life > Methods

Distribution and Movement of Steelhead and Anglers in the Clearwater River, Idaho

AbstractSteelhead Oncorhynchus mykiss is a species that is of high economic value that supports popular sport fisheries across the Pacific Northwest. The Clearwater River in Idaho provides a trophy steelhead fishery, and it is home to both wild‐ and hatchery‐origin steelhead. To manage the fishery effectively, information is needed about the spatial and temporal overlap of wild and hatchery steelhead in the Clearwater River, as well as the activity of anglers. We conducted a radiotelemetry study to describe the distribution of steelhead and their final fate in the Clearwater River, and creel surveys were used to describe the distribution of anglers. In total, 289 wild (Potlatch River and Lochsa River) and hatchery (from Dworshak National Fish Hatchery and South Fork Clearwater River) steelhead were radio‐tagged at Lower Granite Dam, 51 river kilometers (rkm) downstream from the mouth of the Clearwater River. Fish were monitored upon their entry into the Clearwater River by using mobile tracking surveys (boat and vehicle) and stationary antennas. The majority of wild and hatchery steelhead arrived in the Clearwater River in the fall with the exception of those from the Lochsa River, which arrived in the fall and following spring. Average daily movement of the fish was minimal (range = 0.3–4.7 km/d) and dependent on water temperature and flow. The fates of wild and hatchery steelhead varied. Fish returned to spawning grounds, were harvested by anglers (hatchery fish only), or had unknown fates. Both wild and hatchery steelhead returned at high rates to their natal tributaries and release locations. No straying was observed in either group; however, occasions when steelhead have overshot their natal tributaries and release locations were documented. Spatial and temporal overlap of the distributions of wild and hatchery steelhead was minimal. The distribution of anglers overlapped with that of hatchery steelhead in the fall, winter, and spring. The distributional overlap of anglers and wild steelhead was minimal and largely occurred in September in the lower Clearwater River. This suggests that the Clearwater River has a highly compartmentalized fishery and that current fishing regulations in the Clearwater River are providing for a diversity of angling opportunities while conserving wild steelhead and offering harvest of hatchery fish. The results from this study have important implications for the conservation and management of wild and hatchery steelhead.

Stratigraphic and geomorphologic evidence of three MIS 2 glacial advances in the South Fork Hoh River valley, Olympic Mountains, Washington, USA

AbstractThe geomorphology and stratigraphy of the South Fork Hoh River (SF Hoh), Olympic Mountains, Washington, allow for greater understanding of Marine Oxygen Isotope Stage 2 (MIS 2) ice fluctuations, glacial dynamics, and sedimentation. Age control from optically stimulated luminescence and radiocarbon dating constrains deposited sediments associated with four Late Pleistocene ice-marginal positions that formed under reduced ice volume conditions compared with MIS 3–5 glaciers in the same drainage. The earliest MIS 2 ice margin extended into the main Hoh River valley (pre–SF 1, 28 ka to >23.0 ka). After retreat, the ice occupied three closely spaced ice-marginal positions (SF 1–3) that range in age from 22.0 ka to shortly after 18.7 ka. While the SF 1 and SF 3 positions were previously identified as the Twin Creeks I and II positions, the intermediate SF 2 position had not been recognized. Moraines are composed of poorly sorted, but stratified, sediment and few tills. Diamicton units show evidence of water reworking. This research documents a detailed record of MIS 2 glaciation in a maritime setting in western North America and provides evidence of rapid MIS 2 ice-marginal fluctuations that likely reflect responses to millennial-scale climatic fluctuations and may be relevant to understanding other complex MIS 2 moraine sequences.

Satellite L–band vegetation optical depth is directly proportional to crop water in the US Corn Belt

NASA's Soil Moisture Active Passive (SMAP) and ESA's Soil Moisture Ocean Salinity (SMOS) carry satellite L-band radiometers whose primary missions are to measure soil moisture. However, they also allow retrieving of vegetation optical depth (VOD), the degree to which vegetation attenuates microwave radiation. Because attenuation is primarily a function of the total amount of liquid water in a vegetation canopy that is contained within vegetation tissue, VOD could be used to monitor seasonal changes in this quantity, which we call crop water, in major agricultural regions such as the US Corn Belt. There are two main advantages of L-band VOD: it observes the entire canopy volume because soil moisture sensitivity is maintained throughout the growing season; and since it is unaffected by cloud cover there are close to daily measurements. To show its value, we compare SMAP and SMOS VOD to satellite-scale estimates of crop productivity created using the Agricultural Integrated BIosphere Simulator (Agro-IBIS) and observed weather at the South Fork SMAP Core Validation Site in the Corn Belt state of Iowa. We find that SMAP and SMOS VOD are directly proportional to crop water. New empirical models that relate crop water to crop dry mass were required to make this finding. We created these models with in situ data spanning multiple years and stages of crop development. The value of the proportionality constant (or “b-parameter”) relating VOD to crop water at the satellite scale is about half as large as previous estimates. Because L-band VOD is directly proportional to crop water at the satellite scale, and because we understand the relationship between crop water and crop dry mass, SMAP and SMOS have the potential to evaluate the large-scale performance of crop models in the Corn Belt on a near daily basis.

Mesohabitat current velocity effects on Didymosphenia geminata and macroinvertebrates in a SE USA hypolimnetic tailwater

The diatom Didymosphenia geminata is known to alter benthic habitat and macroinvertebrate diversity and community structure. Associations between macroinvertebrate communities and D. geminata biomass in riffle and run mesohabitats were investigated in the South Fork Holston River in Tennessee and Virginia, USA. We found that low current velocity, low turbidity, and high dissolved oxygen (DO) were strong predictors of D. geminata mat presence. Didymosphenia geminata ash-free dry mass was significantly higher in run mesohabitats with low current velocity (CV) than in riffle mesohabitats with higher CV. Macroinvertebrate alpha diversity (Shannon Diversity H’) was only marginally significantly different between riffle and runs, while beta diversity (community composition) was highly significantly different between these mesohabitats. NMDS analyses found that D. geminata was a relatively unimportant predictor of changes in community structure relative to specific conductance, CV, DO, and turbidity. However, effects of D. geminata on macroinvertebrates appear to be very taxon specific with effects on individual taxa potentially masked by tailwater effects on general macroinvertebrate diversity in global analyses. We observed that taxon-specific effects include, but are not limited to, (1) reduction of bryophyte microhabitat utilized by dominant ephemeropterans, trichopterans, amphipods, coleopterans, and some chironomid genera in run mesohabitats from competition with D. geminata for substrate attachment space; and (2) differences in utilization of D. geminata mat biomass as a food resource and microhabitat for chironomids. Our insights into taxon-specific effects of D. geminata on macroinvertebrates open up multiple avenues for experimentation in which to validate our observational findings.

Evaluating definitions of salmonid thermal refugia using in situ measurements in the Eel River, Northern California

AbstractThermal microrefugia, sites within a landscape which are relatively protected from temperature extremes and warming trends, may be necessary for the conservation of animal species as climates warm. In freshwater environments, cold water fish species such as Pacific salmonids already rely on thermal microrefugia to persist in the southern extent of their range. Identifying sites that can provide such thermal microrefugia is essential to inform conservation and management decisions. At present, however, there is no consensus on appropriate ways to identify such sites, and multiple approaches are presented in the literature. Here, we use high resolution thermal data from two cold‐water zones created at the confluence of tributaries with a warm main channel of the South Fork Eel River in Northern California to demonstrate that the characteristics of cold zones identified as thermal microrefugia are not robust to the choice of microrefugium definition. Common definitions disagree on the existence, volume, seasonal temporal trends, and diurnal variations in microrefugia at the two confluences. The disagreements arise from the complex interaction between the confluence mixing regime with diurnal/seasonal warming patterns and how this shapes the distribution of water temperature at the confluences, and how it is classified by each definition. The disagreements cannot be resolved by simple bias correction approaches. Given that all existing definitions rely on simplifications that negate the nuanced way fish use cold water zones and respond to thermal stress, alternative observation and classification approaches may be needed to characterize cold zones in rivers as thermal microrefugia.

Pathobiology and first report of larval nematodes (Ascaridomorpha sp.) infecting freshwater mussels (Villosa nebulosa, Unionidae), including an inventory of nematode infections in freshwater and marine bivalves.

Little information is available on host-parasite relationships between bivalves and larval nematodes. Herein, we describe nematode larvae (likely stage 2) in the infraorder Ascaridomorpha infecting the foot, intestine, and mantle of a freshwater mussel (Alabama rainbow, Villosa nebulosa [Conrad, 1834]) and detail histopathological changes to infected tissues. A total of 43 live mussels from the South Fork of Terrapin Creek, Alabama, were collected between 2010 and 2014, with 14 sectioned for histopathology and 29 dissected. Of the 14 sectioned mussels, 5 appeared to be uninfected, and 7, 1, and 1 had histozoic infections observed in the foot and intestine, intestine only, and mantle edge and foot, respectively. Twenty-three of 29 (79%) of the mussels dissected were infected by live nematodes, and mean nematode abundance was 8.3 (CL = 5.23–13), with 2 mussels infected with >100 nematodes each. Thus, with a total of 32 of the 43 collected mussels observed with nematodes, overall infection prevalence was 74.4% (CL = 0.594–0.855). The 18S rDNA of this nematode was 99% similar to that of several ascaridids (species of Kathlaniidae Lane, 1914 and Quimperiidae Baylis, 1930) that mature in aquatic/semi-aquatic vertebrates; the recovered 18S phylogenetic tree indicated this nematode from V. nebulosa shares a recent common ancestor with Ichthyobronema hamulatum (Ascaridomorpha: Quimperiidae; GenBank Accession Number KY476351). Pathological changes to tissue associated with these infections comprised focal tissue damage, but a cellular response was not evident. The Alabama rainbow possibly represents an intermediate or paratenic host. Given these results, the nematode is likely not pathogenic under normal stream conditions; however, high intensity infections in the foot could inhibit pedal extension and retraction; which would have demonstrable health consequences to a freshwater mussel. Based on our review of the bivalve mollusc parasite literature, a collective biodiversity of 61 nematodes reportedly exhibit some degree of symbiosis (from commensal to parasitic) with 21 bivalves (28 nematode spp. from 17 marine bivalve spp.; 33 nematode spp. from 4 freshwater bivalve spp.); only four records exist of putatively parasitic nematodes from Unionida. The present study represents the first description of a nematode species that invades the tissues of a Unionidae species.

Tree-Ring Reconstructions of Streamflow for the Tennessee Valley

This study reports the preliminary results from a statistical screening of tree-ring width records from the International Tree-Ring Data Bank (ITRDB), to evaluate the strength of the hydrological signal, in dendrochronological records from the Tennessee Valley. We used United States Geological Survey (USGS) streamflow data from 11 gages, within the Tennessee Valley, and regional tree-ring chronologies, to analyze the dendroclimatic potential of the region, and create seasonal flow reconstructions. Prescreening methods included correlation, date, and temporal stability analysis of predictors to ensure practical and reliable reconstructions. Seasonal correlation analysis revealed that large numbers of regional tree-ring chronologies were significantly correlated (p ≤ 0.05) with the May–June–July streamflow. Stepwise linear regression was used to create the May–June–July streamflow reconstructions. Ten of the 12 streamflow stations were considered statistically skillful (R2 ≥ 0.40). Skillful reconstructions ranged from 208 to 301 years in length, and were statistically validated using leave-one-out cross validation, the sign test, and a comparison of the distribution of low flow years. The long-term streamflow variability was analyzed for the Nolichucky, Nantahala, Emory, and South Fork (SF) Holston stations. The reconstructions revealed that while most of the Western United States (U.S.). was experiencing some of its highest flow years during the early 1900s, the Tennessee Valley region was experiencing a very low flow. Results revealed the potential benefit of using tree-ring chronologies to reconstruct hydrological variables in the Southeastern U.S., by demonstrating the ability of proxy-based reconstructions to provide useful data beyond the instrumental record.

Johnstown's Flood of 1889: Power Over Truth and the Science Behind the Disaster, Neil Coleman

<i>Johnstown's Flood of 1889: Power Over Truth and the Science Behind the Disaster</i>, Neil Coleman

Cambarus franklini, a new crayfish (Decapoda: Cambaridae) from the Catawba River Basin in western North Carolina, USA.

A new species of stream-dwelling crayfish, Cambarus franklini, the South Mountains crayfish, is described from the upper South Fork Catawba River basin in western North Carolina, USA using morphological and genetic data. Cambarus franklini was previously considered a member of the widespread and morphologically variable Cambarus species C complex and is morphologically most similar to an undiagnosed member of the group native to the upper Catawba River basin in NC. Cambarus franklini can be differentiated from this species group by several morphological characteristics including: lacking a well-defined double row of tubercles along the mesial margin of the palm, possessing a more weakly convergent and longer acumen, and conspicuous blue-green and red coloration, particularly throughout the telson and along the distal margins of the rami. This species is phylogenetically most similar to Cambarus johni, Cooper, 2006, another former member of the Cambarus species C group. Cambarus franklini has a limited geographic range (100 km2) and is currently known only from the Henry and Jacob Fork watersheds in the South Mountains region of the Eastern Blue Ridge foothills.

Effects of Fishery‐Related Fight Time and Air Exposure on Prespawn Survival and Reproductive Success of Adult Hatchery Steelhead

AbstractIn recent years, increased scrutiny has been placed on the physiological effects of exhaustive exercise and air exposure on caught‐and‐released fish. Steelhead Oncorhynchus mykiss broodstock in the South Fork Clearwater River, Idaho, were collected by anglers during a winter fishery (water temperatures of 2–5°C); this enabled fight and air exposure times to be recorded to determine their influence on prespawn survival and progeny survival to the fry stage in the hatchery. The average fight time during angling was 164 s. Air exposure was measured when anglers landed fish and again during fish transport from the river to the hatchery vehicle; the longest interval of air exposure averaged 23 s during angling and 28 s during transport. Three‐year average prespawn survival was 97.0% for 1,148 angler‐caught fish, compared to 91.9% for 3,325 swim‐in broodstock collected at the hatchery. The top mixed‐effects logistic regression model estimated that the odds of progeny survival increased by 1.027 times with each additional day of the year until an adult fish spawned; this was likely a reflection of peak spawn time in the hatchery. Fight time and air exposure time did not influence progeny survival or prespawn mortality of adult steelhead captured by anglers.

Study on crop residue coverage in the state of Iowa and its importance in regional water supply

Transfer of nutrients and other toxic chemicals from agricultural fields to ground and surface water sources have become a major concern for regional planners in the State of Iowa. It depends on the strength of soil, residue coverage, terrain condition, and annual rainfall. South Fork portion of the Iowa River is fed by Tipton Creek, Honey Creek, Beaver Creek etc. watersheds and this area are located close to cities like Iowa Falls, Marshalltown, and Eldora. Land cover in this area is dominated by corn and soybean production. Presence of higher residue coverage means no-tillage farming practice in agricultural fields and it reduces the force with which raindrops fall on the soil. Correlation between residue coverage and Normalized Difference Tillage Index (NDTI) has been used as the method to identify the presence of tillage practice in agricultural fields. Residue coverage was less than 30% in 352 agricultural fields located adjacent to the South Fork portion of the Iowa River and the positive correlation between NDTI and residue coverage represents the effectiveness of data calculation procedure. A solution of these problems will require both policy and design based initiatives over a long period of time and implementation of existing natural resource management laws.

Differentiating the effects of logging, river engineering, and hydropower dams on flooding in the Skokomish River, Washington, USA

A decades-long, progressive loss of channel capacity in the Skokomish River, a 622 km2 basin draining the southeast Olympic Mountains of Washington State, has caused increasing flooding with severe consequences to endangered salmon runs, infrastructure, and private property. To differentiate among multiple potential drivers of the capacity loss, we analyze the geomorphic evidence for the potential effects of: flow regulation by two dams constituting the Cushman Hydroelectric Project, which began regulating flow in the river's North Fork in 1925 and diverting water out of the basin in 1930; sediment production from mid-twentieth century logging in the river's South Fork basin; and twentieth century river engineering in the mainstem. Bankfull channel capacity in the mainstem has steadily declined since about 1940 from 370 m3 s−1 to <100 m3 s−1 due partly to the narrowing of the Skokomish River, which in 2015 was only 45% as wide as it was in 1938. The capacity loss is also due to sediment filling the channel, with nearly 2 m of aggradation measured at a stream gauge since 1965. Comparison of channel cross sections surveyed in 1994, 2007, and 2016 show that about 20,000 m3 yr−1 (34,000 Mg yr−1) of sediment is accumulating in the Skokomish River. The nature, timing, and spatial pattern of this channel narrowing and shallowing are consistent with the response expected from the Cushman Project, which exports water out of basin and thus substantially reduces downstream flows, but, because the dams were built below a natural lake, does not reduce the sediment supply. While sediment yield from the South Fork is high, accounting for about three-fourths of the total sediment supplied to the Skokomish River, it is dominated by the progressive widening of the channel and recruitment by lateral fluvial erosion of glacial sediments in alluvial terraces; landslides associated with logging in the South Fork basin produced a small amount of sediment relative both to the sediment produced by channel widening in the upper South Fork and to the rate of aggradation in the mainstem Skokomish River. The naturally-high sediment load from the South Fork and the flow reduction in the North Fork result in the unusual effect of flooding having increased downstream of the dams despite substantial reductions to peak flows. This case study illustrates how a watershed-scale analysis of multiple land uses and flow management and their interaction with the basin's geology and geomorphology can make use of geomorphic evidence to differentiate among the possible drivers of channel change and associated flooding.

Isotopic Discrimination of Aquifer Recharge Sources, Subsystem Connectivity and Flow Patterns in the South Fork Palouse River Basin, Idaho and Washington, USA

Groundwater studies in the South Fork Palouse River Basin have been unable to determine recharge sources, subsystem connectivity and flow patterns due to the discontinuity of pathways in the heterogeneous and anisotropic aquifers located in Columbia River flood basalts and interbedded sediments. Major ion, δ18O, δ2H, δ13C, δ34S and temperature for groundwater collected from 28 wells of varying depths indicate a primary recharge source dominated by snowmelt along the eastern basin margin. This recharge can be separated into two distinct sources—a deeper and relatively less altered snowmelt signal (−17.3‰ to −16.8‰ δ18O, −131‰ to −127‰ δ2H, −12.9‰ to −10‰ δ13C, 18–23 °C) and a more altered signal likely derived from a shallower mixture of snowmelt, precipitation and surface water (−16.1‰ to −15.5‰ δ18O, −121‰ to −117‰ δ2H, −15.9‰ to −12.9‰ δ13C, 12–19 °C). A mixing of the shallow and deep source waters is observed within the upper aquifer of the Grande Ronde Formation near Moscow, Idaho, which results in a homogenization of isotope ratios and geochemistry for groundwater at nearly any depth to the west of this mixing zone. This homogenized signal is prevalent in a likely primary productive zone of an intermediate depth in the overall aquifer system.

Upper Sun River Drainage Basin Origin Determined by Topographic Map Interpretation Techniques: Lewis and Clark and Teton Counties, Montana, USA

A new and fundamentally different regional geomorphology paradigm in which massive south- and southeast-oriented meltwater floods flowed across the entire Missouri River drainage basin is tested by interpreting detailed topographic maps of the Montana upper Sun River drainage basin region by trying to explain origins of previously unexplained or poorly explained erosional landforms located upstream from Sun River Canyon (which cuts across Montana’s north-to-south oriented Sawtooth Range). Mountain passes, through valleys, and other drainage divide low points along what are today high mountain ridges, including the North American east-west continental divide, are interpreted to be evidence of drainage routes that once crossed the region. These drainage divide crossings suggest that prior to erosion of present-day upper Sun River drainage basin valleys, massive floods moved in south directions across what are today the north-oriented Middle and South Fork Flathead River drainage basins into today’s upper Sun River drainage basin area and carved a complex of diverging and converging channels into what was probably a low relief surface now represented by the crests of the region’s highest mountain ridges. Further, the map evidence shows how a diverging complex of south- and southeast-oriented upstream Sun River drainage basin flood flow channels changed flow direction to cross the Sawtooth Range in a northeast direction before converging on the Montana plains at a location downstream from Sun River Canyon. The observed upper Sun River drainage basin area topographic map evidence is consistent with the new geomorphology paradigm predictions, in which massive south-oriented meltwater floods flowing across the rising rim of a continental ice sheet created deep “hole” (created by deep ice sheet erosion and ice sheet weight caused crustal warping) are diverted to flow in northeast and north directions into and across deep “hole” space being opened up by ice sheet melting.

Early genetic outcomes of American black bear reintroductions in the Central Appalachians, USA

Habitat loss and overexploitation extirpated American black bears (Ursus americanus) from most of the Central Appalachians, USA, by the early 20th Century. To attempt to restore bears to the southwestern portion of this region, 2 reintroductions that used small founder groups (n = 27 and 55 bears), but different release methods (hard vs. soft), were conducted during the 1990s. We collected hair samples from black bears during 2004–2016 in the reintroduced Big South Fork (BSF) and Kentucky–Virginia populations (KVP), their respective Great Smoky Mountains (GSM) and Shenandoah National Park (SNP) source populations, and a neighboring population in southern West Virginia (SWV) to investigate the early genetic outcomes of bear reintroduction. Despite having undergone genetic bottlenecks, genetic diversity remained similar between reintroduced populations and their sources approximately 15 years after the founder events (ranges: AR = 4.86–5.61; HO = 0.67–0.75; HE = 0.65–0.71). Effective population sizes of the reintroduced KVP and BSF (NE = 31 and 36, respectively) were substantially smaller than their respective SNP and GSM sources (NE = 119 and 156, respectively), supporting founder effects. Genetic structure analysis indicated that the hard-released (i.e., no acclimation period) KVP founder group likely declined considerably, whereas the soft-released BSF founder group remained mostly intact, suggesting superior effectiveness of soft releases. Asymmetrical gene flow via immigration from the SWV has resulted in the KVP recovering from the initial founder group reduction. Sustained isolation, small NE, and small population size of the BSF may warrant continued genetic monitoring to determine if gene flow from neighboring populations is established or NE declines. For future bear reintroductions, we suggest managers consider sourcing founders from populations with high genetic diversity and soft-releasing bears to locales that are, if possible, within the dispersal capability of extant populations to mitigate the potential consequences of founder effects and isolation.

An ecohydraulics virtual watershed: Integrating physical and biological variables to quantify aquatic habitat quality

AbstractAdvances in remote sensing coupled with numerical modelling allow us to build a “virtual ecohydraulics watershed” at the micro‐habitat scale. This approach is an integrated modelling framework with a cascade of models including physical (hydrologic, hydraulic, and stream water temperature) and biological (fish habitat) modelling at a resolution and extent important for aquatic and terrestrial organisms. We applied this approach to quantify the impacts of discharges and water temperature on habitat quality and spatial/temporal habitat use patterns of bull trout, a federally listed species along the South Fork Boise River.We coupled process‐based snow melt and hydrologic models to predict water availability within the watershed. The model fed one‐ and two‐dimensional hydrodynamic models to predict stream hydraulics and water temperature using high‐resolution (meter scale) river bathymetric data. This information was then used in an aquatic habitat modelling to characterize habitat quality distribution as a function of discharges. Our results showed that the summer thermal regime of river system would alter available habitat. The high spatial resolution analysis allows modelling to predict the importance of lateral habitats, which serve as vital refugia during high‐flow events for many fish species. The advances in remote sensing, numerical modelling, and understanding of physical‐biological processes provide us an opportunity to conceptualize new process‐based integrated modelling tools to analyse human impacts at a catchment scale, for example, dam operation and climatic variability on aquatic habitat and status, and further to develop restoration protocols in a virtual domain before field studies are developed and/or structures built.

A Five-Year Evaluation of SMOS Level 2 Soil Moisture in the Corn Belt of the United States

We compare Soil Moisture Ocean Salinity Level 2 Soil Moisture (L2SM) retrievals to the five-year in situ soil moisture dataset available for the predominately agricultural South Fork Iowa River (SFIR) watershed in the U. S. Corn Belt. SMOS L2SM is 0.039 m $^3$ m $^{-3}$ drier than the SFIR network soil moisture and has an unbiased RMSE (ubRMSE) of 0.062 m $^3$ m $^{-3}$ for the period of April 2013 to November 2017 (excluding DJF). The bias is 11% of the range of in situ soil moisture. The largest monthly dry biases occur in April (0.052 m $^3$ m $^{-3}$ ), July (0.072 m $^3$ m $^{-3}$ ), and November (0.061 m $^3$ m $^{-3}$ ). Potential sources of the dry bias we discuss are: bias in auxiliary modeled temperatures; errors in soil texture maps; and nonrepresentative parameterizations of single scattering albedo and soil surface roughness. Auxiliary skin temperature was colder than expected and may explain why SMOS L2SM has a slightly drier bias for evening overpasses. Increasing the parameterized soil surface roughness produces wetter SMOS L2SM retrievals but also decreases the range of SMOS L2SM. Random error in auxiliary surface temperature, edge-of-field locations of in situ sensors, and differences in sensing volume between SMOS and in situ sensors contribute to the soil moisture ubRMSE. ubRMSE can be decreased by using a nonzero single scattering albedo more representative of a corn and soybean canopy at the cost of increasing the dry bias.